When performing the bench press, many lifters experience pain in the posterior shoulder, often identified as the rear deltoid. This discomfort frequently signals a mechanical imbalance or technical flaw, rather than a simple muscle strain. While not the primary muscle driving the weight, the rear deltoid’s function is directly related to the stability of the shoulder complex during pressing movements. Understanding its role and identifying the root causes of strain is the first step toward pain-free pressing.
How the Rear Deltoid Stabilizes the Lift
The rear deltoid’s function during the bench press is primarily stabilization. Its most significant role is preventing the head of the humerus (upper arm bone) from gliding too far forward in the shoulder socket during the movement. This mechanism is especially important during the eccentric phase of the lift (as the bar is lowered), when the shoulder is most vulnerable to strain.
When the chest muscles contract to press the weight upward, the rear deltoid resists the anterior shift of the shoulder joint, maintaining proper alignment. Weakness or poor endurance in this muscle can manifest as a shaky bar path, particularly with heavier loads. If the rear deltoid cannot adequately stabilize the joint, the rotator cuff muscles must compensate, leading to inflammation, irritation, or impingement. The pain felt in the rear deltoid is often a sign that this stabilizer muscle is overworked.
Common Technique Errors Causing Pain
Rear deltoid pain frequently stems from improper setup and execution, placing undue stress on the posterior shoulder stabilizers. Failing to properly retract and depress the shoulder blades throughout the lift is a primary error. This packed position creates a solid, stable base, and losing it allows the humerus to move forward, causing strain and potential impingement at the bottom of the movement.
Excessive elbow flare is another common mistake, where the elbows travel out to a 90-degree angle relative to the torso at the bottom of the lift. This wide angle forces the shoulder into a vulnerable, internally rotated position under load, significantly increasing stress on the anterior shoulder and stabilizing rear muscles. The safer position involves tucking the elbows closer to 45 to 75 degrees, keeping the shoulder joint less compromised.
Grip width also plays a role in shoulder mechanics; a grip that is too wide increases the range of motion and overall torque on the shoulder joint. This forces the rear deltoid to work harder to maintain stability across a greater distance, which can lead to fatigue and pain. Similarly, an incorrect bar path, such as touching the bar too high on the chest, increases the compressive forces on the clavicle and the net torque on the shoulder. The bar should ideally travel in a slight diagonal path, touching the chest around the sternum or nipple line.
Relying on momentum or bouncing the bar off the chest compromises the eccentric control provided by the rear deltoid. The posterior deltoid is most engaged at the bottom of the movement, resisting the forward movement of the arm. Bouncing the bar eliminates the controlled lowering phase and introduces an abrupt shock, instantly overloading the stabilizing muscles and connective tissues. Consistent use of poor form creates a cumulative strain that results in acute pain or chronic injury.
Immediate Acute Pain Management
When acute pain strikes in the rear deltoid during a bench press, the first step is to immediately stop the painful exercise. Continuing to push through sharp or radiating pain risks turning a minor strain into a more significant injury. The painful activity should be avoided for several days to allow the inflamed tissue to begin the healing process.
The R.I.C.E. protocol—Rest, Ice, Compression, and Elevation—can be used to manage the immediate symptoms of inflammation and pain. Applying an ice pack to the affected area for about 20 minutes every few hours can help reduce local swelling and numb the pain. While compression and elevation are often less practical for the shoulder joint, resting the arm and limiting motion is paramount.
Pain relievers, such as acetaminophen, can be taken for symptomatic relief, though non-steroidal anti-inflammatory drugs (NSAIDs) may be used initially to address inflammation. If the pain is sharp, accompanied by a loss of function, or does not begin to resolve after five to seven days of rest and conservative management, professional medical advice should be sought. During this acute phase, pressing movements should be avoided, and training can be temporarily modified to include light, machine-based work or lower-body exercises.
Corrective Exercises for Long-Term Relief
Addressing rear deltoid pain requires a long-term strategy focused on strengthening the posterior shoulder girdle and improving overall shoulder mobility. Direct rear deltoid strengthening exercises are performed to balance the strength typically dominated by the anterior chest and deltoid muscles. Effective isolation movements include the Face Pull, which targets the rear delts, rhomboids, and upper back, and the Reverse Fly (or Rear Delt Fly) performed on a machine or bent-over with dumbbells.
These isolation exercises should generally be performed with lighter weight and higher repetitions to promote muscular endurance and blood flow, rather than focusing on heavy lifting. For instance, performing band pull-aparts for high volume before a pressing session can effectively “prime” the posterior muscles, ensuring they are engaged and ready to stabilize the joint. The goal is to establish a strong mind-muscle connection and generate a burn in the target area.
Rotator cuff health must also be prioritized, as these muscles work intimately with the rear deltoid for joint stability. Exercises like side-lying external rotations, performed with a very light dumbbell or resistance band, directly target the infraspinatus and teres minor, which are crucial external rotators. This movement strengthens the muscles responsible for keeping the humerus centered in the socket during the bench press.
Finally, improving thoracic spine mobility is often overlooked but plays a significant role in safe bench press technique. A stiff upper back can prevent the necessary scapular retraction and depression, forcing the shoulders to round forward. Incorporating movements that promote T-spine extension and rotation, such as foam rolling or mobility drills, can help the lifter achieve a better setup position. These corrective exercises should be integrated consistently into a warm-up routine or performed on separate training days for optimal long-term joint health.